EP0479278B1 - Zylindrische Magnetanordnung geeignet für die Bilderzeugung mittels magnetischer Kernresonanz - Google Patents

Zylindrische Magnetanordnung geeignet für die Bilderzeugung mittels magnetischer Kernresonanz Download PDF

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Publication number
EP0479278B1
EP0479278B1 EP91116845A EP91116845A EP0479278B1 EP 0479278 B1 EP0479278 B1 EP 0479278B1 EP 91116845 A EP91116845 A EP 91116845A EP 91116845 A EP91116845 A EP 91116845A EP 0479278 B1 EP0479278 B1 EP 0479278B1
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EP
European Patent Office
Prior art keywords
magnet
segments
dipole ring
ring magnets
dipole
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Expired - Lifetime
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EP91116845A
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English (en)
French (fr)
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EP0479278A1 (de
Inventor
Koji Miyata
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Shin Etsu Chemical Co Ltd
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Shin Etsu Chemical Co Ltd
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Priority claimed from JP2267448A external-priority patent/JP2787509B2/ja
Priority claimed from JP2267446A external-priority patent/JPH04144540A/ja
Priority claimed from JP2267447A external-priority patent/JPH04144541A/ja
Application filed by Shin Etsu Chemical Co Ltd filed Critical Shin Etsu Chemical Co Ltd
Publication of EP0479278A1 publication Critical patent/EP0479278A1/de
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/02—Permanent magnets [PM]
    • H01F7/0273—Magnetic circuits with PM for magnetic field generation
    • H01F7/0278—Magnetic circuits with PM for magnetic field generation for generating uniform fields, focusing, deflecting electrically charged particles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
    • G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
    • G01R33/383—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using permanent magnets

Definitions

  • This invention relates to a cylindrical magnet apparatus for producing a magnetic field in a predetermined direction within the cylindrical bore of the apparatus.
  • the apparatus is a coaxial assembly of a plurality of dipole ring magnets, and each ring magnet is constructed of a plurality of annularly arranged segments each of which is an anisotropic magnet block.
  • the apparatus is suitable for use in nuclear magnetic resonance (NMR) imaging, and particularly in computerized tomography (CT) apparatus utilizing NMR.
  • NMR nuclear magnetic resonance
  • CT computerized tomography
  • each dipole ring magnet is formed by annularly assembling a plurality of anisotropic magnet blocks which are respectively magnetized in suitable directions.
  • the magnet material for the aforementioned dipole ring magnets either a conventional ferrite magnet or a rare earth alloy magnet is used.
  • a ferrite magnet When a ferrite magnet is used the ring magnets need to be made very large in outer diameters so that the gross weight of the assembly of the ring magnets become very heavy.
  • a rare earth alloy metal it is possible to greatly reduce the total weight of the ring magnets, but nevertheless there arises a great increase in the material cost because of very high price of the rare earth alloy magnet per unit weight.
  • a permanent magnet NMR imaging apparatus comprises a plurality of dipole ring magnets each dipole ring magnet comprising a plurality of segments each segment comprising an oriented, anisotropic permanent magnet material arranged in a ring so that there is a substantially continuous ring of permanent magnet material.
  • EP-A-0 262 880 discloses a magnetic field generating device for NMR-CT.
  • This device comprises a pair of disk-like permanent magnets held opposite to each other.
  • Each magnet disk is composed of a ferrite magnet and a rare earth magnet.
  • a central part of each magnet disk is made of a ferrite magnet and the remaining peripheral part of a rare earth magnet.
  • a central part of each magnet disk is made of a rare earth magnet and the remaining peripheral parts of a ferrite magnet. Both ferrite and rare earth magnets are used in any part of a disk-like permanent magnet.
  • the present invention relates to a cylindrical magnet apparatus which is an assembly of a plurality of dipole ring magnets each of which is formed of a plurality of anisotropic magnet blocks and can be used in NMR-CT apparatus, and it is an object of the invention to provide an improved cylindrical magnet apparatus which is relatively light in the total weight of magnet and reasonably economical in magnet material cost. This object is solved with the features of the claims.
  • the present invention provides a magnet apparatus suitable for use in NMR imaging, and particularly in NMR-CT apparatus.
  • the magnet apparatus is an assembly of a plurality of dipole ring magnets having substantially the same inner diameter in a coaxially juxtaposed arrangement.
  • Each of the dipole ring magnets is constructed of a plurality of segments which are arranged annularly, and each segment is an anisotropic magnet block which has a trapezoidal cross-sectional shape and is magnetized in a suitable direction before constructing the dipole ring magnet such that a magnetic field in a predetermined direction is produced in the hole of each dipole ring magnet.
  • a selected portion of the assembly of dipole ring magnets is made of a rare earth alloy magnet whereas the remaining portion of the assembly is made of a ferrite magnet.
  • each segment of each dipole ring magnet an end part on the radially inner side of the ring magnet is made of a rare earth alloy magnet whereas the remaining part of the segment is made of a ferrite magnet.
  • the plurality of segments are all made of a rare earth alloy magnet whereas in each of the remaining dipole ring magnet(s) the plurality of segments are all made of a ferrite magnet.
  • each dipole ring magnet only two segments in which the direction of magnetization is parallel to the predetermined direction of the magnetic field produced in the hole of each dipole ring magnet are made of a ferrite magnet whereas the remaining segments are made of a rare earth alloy magnet.
  • the present invention utilizes both a ferrite magnet, which is inexpensive despite the need of using a relatively large weight because of relatively low magnetic characteristics, and a rare earth alloy magnet which is expensive but is superior in magnetic characteristics and hence contributes to a reduction in the total weight of the magnet apparatus.
  • FIGs. 1 and 2 show a magnetic field producing apparatus 10 which is an assembly of five dipole ring magnets 100, 200, 300, 400, 500 in a coaxially juxtaposed arrangement.
  • the five ring magents have the same inner diameter so that the apparatus 10 has a cylindrical hole.
  • the ring magnet 100 at one end of the apparatus 10 is constructed of sixteen segments 101, 102, ..., 116 which are arranged annularly and bonded to each other.
  • Each of these sixteen segments 101, 102, ..., 116 is an anisotropic magnet block having a trapezoidal cross-sectional shape.
  • an end part on the radially inner side of the ring magnet 100 is made of a rare earth alloy magnet 12, and the remaining part on the radially outer side is made of a ferrite magnet 14.
  • the respective segments are magnetized in the directions indicated by arrows S such that the ring magnet 100 is magnetized in the direction indicated by arrow M.
  • each of the remaining four ring magnets 200, 300, 400, 500 is constructed of sixteen segments each of which is an anisotropic magnet block having a trapezoidal cross-sectional shape, and in every segment an end part on the radially inner side of the ring magnet is made of the rare earth alloy magnet 12 whereas the remaining part is made of the ferrite magnet 14.
  • the directions of magnetization of the respective segments are as indicated by arrows S in Fig. 1.
  • a radially inner part of the ring magnets 100, 200, ..., 500 serves a more important role than the radially outer part.
  • the rare earth alloy magnet 12 which is an expensive material, is used only for the radially inner part of each ring magnet 100, 200, ..., 500.
  • the ferrite magnet 14 is used for the remaining part of each ring magnet.
  • each ring magnet becomes higher as the proportion of the rare earth alloy magnet 12 to the ferrite magnet 14 is increased, whereas the volume of the ferrite magnet 14 must be increased as the proportion of the rare earth alloy magnet 12 is decreased. Therefore, the rare earth alloy magnet 12 is used to such an extent that the gross weight of each ring magnet does not unduly increase.
  • the rare earth alloy magnet 12 can be selected from known rare earth alloy magnets.
  • a preferred example is Nd-Fe-B magnet composed of 10-30 mol% of Nd, 60-85 mol% of Fe and 2-25 mol% of B.
  • each ring magnet 100, 200, ..., 500 the sixteen trapezoidal segments (e.g. 101 to 116 in ring magnet 100) are dissimilar in height (i.e. length in the direction radially of the ring magnet).
  • an optimum height can be determined according to the intended intensity of magnetization of that segment by using the mathematical programming method.
  • the ring magnets 100 and 500 at the opposite ends of the cylindrical apparatus 10 need to be relatively large in outer diameters and hence in volume.
  • these ring magnets 100, 500 are distant from the aforementioned central region 16 where a very uniform magnetic field is to be produced, the magnetic influence of a unit volume of these magnets 100, 500 on the cnetral region 16 is relatively weak, and accordingly the magnets 100, 500 must have a relatively large volume.
  • Figs. 3 and 4 show a conventional magnetic field producing apparatus 10A which is fundamentally similar to the apparatus 10 shown in Figs. 1 and 2. That is, this apparatus 10A is an assembly of five dipole ring magnets 100A, 200A, 300A, 400A, 500A, and each ring magnet is constructed of sixteen cross-sectionally trapezoidal segments, such as segments 101A, 102A, ..., 116A of the ring magnet 100A, each of which is an anisotropic magnet block.
  • every segment of each ring magnet is entirely made of a ferrite magnet. Therefore, compared with the ring magnets 100, 200, ..., 500 in Fig. 2 the ring magnets 100A, 200A, ..., 500A in Fig. 4 need to be made larger in outer diameters.
  • the ring magnets 100A and 500A at the two ends of the apparatus 10A need to be made very larger in outer diameters.
  • the inner diameter D was 800 mm
  • the axial lengths of the respective ring magnets 100A, 200A, ..., 500A were as follows.
  • L 3 400 mm
  • the ferrite magnet was of the following characteristics.
  • FIG. 10A For comparison, another example of the apparatus 10A of Figs. 3 and 4 was constructed by using a rare earth alloy magnet, viz. Nd-Fe-B magnet of the following characteristics, as the sole magnet material for the entirety of the ring magnets 100A, 200A, ..., 500A.
  • a rare earth alloy magnet viz. Nd-Fe-B magnet of the following characteristics, as the sole magnet material for the entirety of the ring magnets 100A, 200A, ..., 500A.
  • the inner diameter D of the apparatus was 800 mm, and the lengths L 1 , L 2 , L 3 , L 4 and L 5 of the respective ring magnets 100, 200, ..., 500 were the same as in the examples of the apparatus 10A in Figs. 3 and 4, viz. 300 mm, 300 mm, 400 mm, 300 mm and 300 mm, respectively.
  • the ferrite magnet used in the first example of the apparatus of Figs. 3 and 4 and the Nd-Fe-B magnet used in the second example were used also in this example.
  • the ring magnets 100, 200, ..., 500 were designed so as to realize a uniform field of 2000 G in the central spherical region 16 of the apparatus 10 having a diameter of 400 mm.
  • the total weight of the ferrite magnet 14 and the Nd-Fe-B magnet 12 in Figs. 1 and 2 amounted to about 3850 kg, which means that the cost reduction was accompanied by an increase in weight by about 1000 kg and that the increased weight was still far less than the weight (12300 kg) of the first exmple of the apparatus of Figs. 3 and 4 using the ferrite magnet.
  • the joint use of the ferrite magnet and the rare earth alloy magnet raised no problem in respect of the construction and performance of the apparatus 10.
  • Figs. 5 and 6 show a second embodiment of the invention.
  • particular attension was paid to the very large outer diameters of the two ring magnets 100A and 500A at the two ends of the known apparatus 10A of Figs. 3 and 4 using a ferrite magnet.
  • the apparatus 10 of Figs. 5 and 6 also is a coaxial assembly of five dipole ring magnets 100, 200, 300, 400, 500, and each ring magnet is constructed of sixteen cross-sectionally trapezoidal segments, such as segments 101, 102, ..., 116 of the ring magnet 100 and segments 201, 202, ..., 216 of the ring magnet 200, each of which is an anisotropic magnet block.
  • every segment of these two ring magnets 100, 500 is made of a rare earth alloy magnet.
  • every segment of the remaining three ring magnets 200, 300, 400 is made of a ferrite magnet. Since a rare earth alloy magnet superior in magnetic characteristics is used, the two ring magnets 100 and 500 can be made considerably smaller in outer diameters compared with the counterparts (100A and 500A) in Figs. 3 and 4.
  • the inner diameter D of the apparatus was 800 mm, and the lengths L 1 , L 2 , L 3 , L 4 and L 5 were the same as in the foregoing examples, viz. 300 mm, 300 mm, 400 mm, 300 mm and 300 mm, respectively.
  • All the segments of the two ring magnets 100 and 500 were made of the Nd-Fe-B magnet used in the foregoing examples, and all the segments of the remaining three ring magnets 200, 300, 400 were made of the ferrite magnet used in the foregoing examples.
  • the ring magnets 100, 200, ..., 500 were respectively designed so as to realize a uniform field of 2000 G in the central spherical region 16 of the apparatus 10 having a diameter of 400 mm. It was possible to greatly decrease the outer diameters of the two ring magnets 100 and 500. The total weight of the five ring magnets became 7150 kg. That is, compared with the first example of the apparatus 10A of Figs. 3 and 4 using the ferrite magnet alone, the gross weight of the apparatus decreased by more than 5000 kg.
  • the use of the Nd-Fe-B magnet for the two ring magnets 100, 500 caused an about 40% increase in the magnet material cost, but the amount of the increase is very small by comparison with the case of using the rare earth alloy magnet for the entirety of the five ring magnets.
  • FIGs. 7 and 8 show a third embodiment of the invention.
  • This apparatus 10 also is a coaxial assembly of five dipole ring magnets 100, 200, 300, 400, 500, and each ring magnet is constructed of sixteen cross-sectionally trapezoidal segments, such as segments 101, 102, ..., 116 of the ring magnet 100, each of which is an anisotropic magnet block.
  • the segment 105 and the segment 113 positioned opposite to the segment 105 are made of a ferrite magnet.
  • the direction of magnetization indicated by arrows S is parallel to the direction of a uniform magnetic field, indicated by arrow M, produced in the hole of the dipole ring magnet 100.
  • the remaining fourteen segments of the ring magnet 100 are all made of a rare earth alloy magnet.
  • the reason for using the inexpensive ferrite magnet only for the two specific segments 105 and 113 is that these two segments do not serve an important role in producing a uniform magnetic field in the ring magnet 100, and hence in the bore of the apparatus 10, because of the parallelness of the direction of magnetization S to the direction M of the uniform magnetic field.
  • segments 205 and 213 of the ring magnet 200, segments 305 and 313 of the ring magnet 300, segments 405 and 413 of the ring magnet 400 and segments 505 and 513 of the ring magnet 500 are made of the ferrite magnet.
  • five dipole ring magnets are used to construct an apparatus according to the invention, but this is not limitative.
  • the number of the ring magnets can be increased or decreased.
  • always an odd number of ring magnets should be used since it is intended to produce a uniform magnetic field in an central region of the cylindrical hole in the apparatus.
  • axially end regions of two adjacent ring magnets surround a central region of the cylindrical hole, and this is unfavorable for uniformity of the magnetic field produced in the central region.
  • each dipole ring magnet should be constructed of an even number of cross-sectionally trapezoidal segments each of which is an anisotropic magnet block.
  • the even number of segments are designed and arranged such that the inner circumference of the ring magnet is divided into equal n parts (n is the number of the segments) and such that every two segments positioned opposite to each other (with respect to the center axis of the ring magnet) are symmetrical in shape and identical in dimensions including the height (length in the direction radially of the ring magnet).
  • each ring magnet the minimum number of the segments will be four, but usually a larger number of segments are used by dividing each of the four segments into two halves and, according to the need, further halving the respective halves.
  • the number of segments is a multiple of 8, such as 8, 16 or 32.
  • For uniformity of a magnetic field produced in the hole of each dipole ring magnet it is favorable to increase the number of segments (anisotropic magnet blocks), but the magnetic circuits become intricate as the number of segments is increased. In the practice of the invention it suffices to divide each ring magnet into 32 segments at the maximum.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Claims (21)

  1. Zylindermagnetvorrichtung (10), die zur Verwendung in der Kernspintomographie geeignet ist, wobei die Vorrichtung eine Zusammenstellung aus mehreren Dipolringmagneten (100, 200...) mit im wesentlichen dem gleichen Innendurchmesser in einer gleichachsig nebeneinanderliegenden Anordnung ist, jeder der Dipolringmagneten aus mehreren Segmenten (101, 102...) aufgebaut ist, die ringförmig angeordnet sind, jedes der Segmente ein anisotroper Magnetblock ist, der eine trapezförmige Querschnittform hat und vor Aufbau des Dipolringmagneten so in einer geeigneten Richtung magnetisiert ist, daß ein Magnetfeld in einer vorbestimmten Richtung (M) in dem Loch jedes Dipolringmagneten erzeugt wird,
    dadurch gekennzeichnet, daß in jedem der Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) ein Endteil auf der radialen Innenseite des Ringmagneten aus einem Seltenerde-Legierungsmagneten (12) hergestellt ist, während der übrige Teil des Segments aus einem Ferritmagneten (14) hergestellt ist.
  2. Vorrichtung nach Anspruch 1, wobei die Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) eine ungleichartige Länge in Radialrichtung des Ringmagneten haben, und die Länge jedes Segments entsprechend der Magnetisierungsstärke des Segments bestimmt ist.
  3. Vorrichtung nach Anspruch 1 oder 2, wobei die Anzahl der Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) eine gerade Zahl ist, und in jedem der Dipolringmagneten jeweils zwei Segmente, die einander bezüglich der Mittelachse des Ringmagneten entgegengesetzt sind, eine symmetrische Form und die gleiche Länge in Radialrichtung des Ringmagneten haben.
  4. Vorrichtung nach Anspruch 3, wobei die gerade Zahl ein Vielfaches von 8 ist.
  5. Vorrichtung nach Anspruch 4, wobei die gerade Zahl nicht größer als 32 ist.
  6. Vorrichtung nach einem der Ansprüche 1 bis 5, wobei die Anzahl der Dipolringmagneten (100, 200...) eine ungerade Zahl ist.
  7. Vorrichtung nach einem der Ansprüche 1 bis 6, wobei der Seltenerde-Legierungsmagnet (12) ein Nd-Fe-B-Magnet ist.
  8. Zylindermagnetvorrichtung (10), die zur Verwendung in der Kernspintomographie geeignet ist, wobei die Vorrichtung eine Zusammenstellung aus mindestens drei Dipolringmagneten (100, 200...) mit im wesentlichen dem gleichen Innendurchmesser in einer gleichachsig nebeneinanderliegenden Anordnung ist, jeder der Dipolringmagneten aus mehreren Segmenten (101, 102...) aufgebaut ist, die ringförmig angeordnet sind, jedes der Segmente ein anisotroper Magnetblock ist, der eine trapezförmige Querschnittform hat und vor Aufbau des Dipolringmagneten so in einer geeigneten Richtung magnetisiert ist, daß ein Magnetfeld in einer vorbestimmten Richtung (M) in dem Loch jedes Dipolringmagneten erzeugt wird,
    dadurch gekennzeichnet, daß in einem (100) der Dipolringmagneten, der an einem Ende der Zusammenstellung positioniert ist, und in einem weiteren (500) der Dipolringmagneten, der an dem entgegengesetzten Ende der Zusammenstellung positioniert ist, jedes der Segmente aus einem Seltenerde-Legierungsmagneten (12) hergestellt ist, während in jedem der übrigen Dipolringmagneten jedes der Segmente aus einem Ferritmagneten (14) hergestellt ist.
  9. Vorrichtung nach Anspruch 8, wobei die Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) eine ungleichartige Länge in Radialrichtung des Ringmagneten haben, und die Länge jedes Segments entsprechend der Magnetisierungsstärke des Segments bestimmt ist.
  10. Vorrichtung nach Anspruch 8 oder 9, wobei die Anzahl der Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) eine gerade Zahl ist, und in jedem der Dipolringmagneten jeweils zwei Segmente, die einander bezüglich der Mittelachse des Ringmagneten entgegengesetzt sind, eine symmetrische Form und die gleiche Länge in Radialrichtung des Ringmagneten haben.
  11. Vorrichtung nach Anspruch 10, wobei die gerade Zahl ein Vielfaches von 8 ist.
  12. Vorrichtung nach Anspruch 11, wobei die gerade Zahl nicht größer als 32 ist.
  13. Vorrichtung nach einem der Ansprüche 8 bis 12, wobei die Anzahl der Dipolringmagneten (100, 200...) eine ungerade Zahl ist.
  14. Vorrichtung nach einem der Ansprüche 8 bis 13, wobei der Seltenerde-Legierungsmagnet (12) ein Nd-Fe-B-Magnet ist.
  15. Zylindermagnetvorrichtung (10), die zur Verwendung in der Kernspintomographie geeignet ist, wobei die Vorrichtung eine Zusammenstellung aus mehreren Dipolringmagneten (100, 200...) mit im wesentlichen dem gleichen Innendurchmesser in einer gleichachsig nebeneinanderliegenden Anordnung ist, jeder der Dipolringmagneten aus mehreren Segmenten (101, 102...) aufgebaut ist, die ringförmig angeordnet sind, jedes der Segmente ein anisotroper Magnetblock ist, der eine trapezförmige Querschnittform hat und vor Aufbau des Dipolringmagneten so in einer geeigneten Richtung magnetisiert ist, daß ein Magnetfeld in einer vorbestimmten Richtung (M) in dem Loch jedes Dipolringmagneten erzeugt wird,
    dadurch gekennzeichnet, daß von den Segmenten jedes der Dipolringmagneten nur zwei Segmente (113, 105), in denen die Magnetisierungsrichtung (S) parallel zu der vorbestimmten Richtung (M) des in dem Loch jedes Dipolringmagneten (100, 200...) erzeugten Magnetfelds ist, aus einem Ferritmagneten (14) hergestellt sind, während die übrigen Segmente aus einem Seltenerde-Legierungsmagneten (12) hergestellt sind.
  16. Vorrichtung nach Anspruch 15, wobei die Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) eine ungleichartige Länge in Radialrichtung des Ringmagneten haben, und die Länge jedes Segments entsprechend der Magnetisierungsstärke des Segments bestimmt ist.
  17. Vorrichtung nach Anspruch 15 oder 16, wobei die Anzahl der Segmente (101, 102...) jedes der Dipolringmagneten (100, 200...) eine gerade Zahl ist, und in jedem der Dipolringmagneten jeweils zwei Segmente, die einander bezüglich der Mittelachse des Ringmagneten entgegengesetzt sind, eine symmetrische Form und die gleiche Länge in Radialrichtung des Ringmagneten haben.
  18. Vorrichtung nach Anspruch 17, wobei die gerade Zahl ein Vielfaches von 8 ist.
  19. Vorrichtung nach Anspruch 18, wobei die gerade Zahl nicht größer als 32 ist.
  20. Vorrichtung nach einem der Ansprüche 15 bis 19, wobei die Anzahl der Dipolringmagneten (100, 200...) eine ungerade Zahl ist.
  21. Vorrichtung nach einem der Ansprüche 15 bis 20, wobei der Seltenerde-Legierungsmagnet (12) ein Nd-Fe-B-Magnet ist.
EP91116845A 1990-10-04 1991-10-02 Zylindrische Magnetanordnung geeignet für die Bilderzeugung mittels magnetischer Kernresonanz Expired - Lifetime EP0479278B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP267447/90 1990-10-04
JP267446/90 1990-10-04
JP2267448A JP2787509B2 (ja) 1990-10-04 1990-10-04 磁場発生装置
JP267448/90 1990-10-04
JP2267446A JPH04144540A (ja) 1990-10-04 1990-10-04 磁場発生装置
JP2267447A JPH04144541A (ja) 1990-10-04 1990-10-04 磁場発生装置

Publications (2)

Publication Number Publication Date
EP0479278A1 EP0479278A1 (de) 1992-04-08
EP0479278B1 true EP0479278B1 (de) 1998-01-21

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DE (1) DE69128758T2 (de)

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FR2962846B1 (fr) * 2010-07-16 2014-10-17 Commissariat Energie Atomique Dispositif d'aimant permanent de creation d'un champ magnetique homogene deporte
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JP5623368B2 (ja) * 2010-11-05 2014-11-12 信越化学工業株式会社 ダイポールリング磁気回路
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ITUB20155325A1 (it) * 2015-10-26 2017-04-28 Sotgiu Antonello Magnete per diagnostica clinica tramite risonanze magnetiche (MRI) composto da anelli cilindrici di tipo Halbach: modalita di costruzione e tecniche per rendere omogeneo il campo magnetico in una larga frazione del volume interno del magnete.
CN106601427B (zh) * 2017-01-12 2018-07-24 中国科学院上海硅酸盐研究所 均匀磁场发生器
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US5148138A (en) 1992-09-15
DE69128758T2 (de) 1998-05-14
EP0479278A1 (de) 1992-04-08

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